In chemical equipment such as a petroleum distillation and refinery plant, a polyolefin manufacturing plant (equipment for producing polyolefin) and the like, problems such as reduction of heat-exchange capability of the plant, blockage of pipes, or the like may occur due to fouling. These problematic phenomena are desired to be avoided since manufacturing operation may become unstable and, in the worst case, may fall into shutdown thereby.
In particular, various known methods such as a liquid-phase polymerization, a gas-phase polymerization and the like are used in a polyolefin production process. (Co)polymers are obtained in a form of powder in a gas-phase polymerization. Also in a liquid-phase polymerization, the obtained (co)polymers are often collected in a form of powder, because of the ease in handling. (The term “(co)polymer” herein encompasses both a homopolymer and a copolymer, and this definition is also applied to the below).
Thus, a polymer powder is desired to have an excellent fluidity in a closed space in which the polymer powder exists (e.g., a polymerization reaction vessel or pipes for producing a polymer powder in a gas-phase polymerization, a storage facility for storing a polymer powder which is obtained in a liquid-phase polymerization or a gas-phase polymerization, etc.) without causing fouling.
Polyolefins such as polyethylene, polypropylene, ethylene/α-olefin copolymers, and propylene/α-olefin copolymers are produced by (co)polymerizing olefins in the presence of a solid catalyst such as a solid titanium catalyst or a carrier-supported metallocene catalyst. These solid catalysts often have a low fluidity and may be hardly fed into a polymerization vessel. Such problems can be improved to some extent by having a surfactant be supported on the solid catalysts, but this may cause a problem of reduction of the polymerization activity.
When gas-phase polymerization of olefins is carried out in the presence of the solid catalyst, the mixing state in the fluidized bed may become nonhomogeneous due to generation of polymer lumps, sheet-like matters or the like in a fluidized bed, or reduction of the fluidity of polyolefin powder, which may cause problems such as inhibiting a long-term stable operation.
In addition, various subsequent processes may be interrupted by formation of bridges in a storage facility or the like for collecting and/or storing the finally obtained polymer powders due to occurence of bonding of polymer powders caused by reduction of fluidity of the polymer powders in the storage facility.
With respect to these issues, Japanese Patent Application Laid-Open (JP-A) No. 2000-313717 discloses a method comprising adding a higher aliphatic amide into a powder flowing environment field in polyolefin production.
JP-A No. 2005-48175 discloses a method for preventing fouling in a heat exchanger by a method comprising adding a nonionic surfactant into a component in chemical equipment.